Trib Ology Roller

8/10/2019 Trib Ology Roller

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Lubrication

Of

Roller Bearings


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Roller Bearings have a long history

around 700 BC

1794

186940 AC

around

3000 BC


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Tasks of Roller Bearings

lreducing fr ict ion

ltransfer o f loads

lguiding rotat ing parts


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Friction


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Energy losses through friction

10 % = 1/2 E [AUS+BR+E+S]

Although rolling friction is already very low, manufacturers of roller

bearings and lubricants work continuously on further improvements..

SKFone of the worlds biggest manufacturers of roller

bearings

made the following calculation:

If it can be managed to drop the friction in all roller bearings

installed on the globe only by further 10%,

the combined total electricity consumption of the countries

Australia, Brasil, Spain und Sweden

could be cut to a half !


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Roller Bearings are named after theShape of their rolling Elements

ball spherical roller

symmetrical

spherical roller

asymmetrical

cylindrical roller

needle roller

conical roller


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Friction in Roller Bearings

lsm all por t ion of ro l l ing fr ic t ion

lbu t con siderable share of sl id ing fr ict io n at:

roller bearing rings

cages and / or

rolling elements against each other


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Kinds of Lubricationof Roller Bearings

9,5% by oi ls 0,5% by sol id lubr icants o nly

90% b y greases


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DN- Factors for OKS Bearing Greases


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Temperature Range of OKS BearingGreases

with MoS2

with MoS2+ Mox- Active

with MoS2

with Mox- Active

with MoS2+ Mox- Active

with PTFE

with PTFE

with white solid lubricants

with PTFE


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Lubrication by greases

Grease pump

Contamination may

cause bearing failures.

Seals protect to a large

extent from outside contaminations.Frequent relubrication is required when

the hazard of grease contamination exists.Same applies if the grease should seal also

against penetrating moisture.

Contamination penetrating through

labyrinth channels.

Newly supplied grease pushes out both

used up and contaminated grease

through the labyrinth packing seals.


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Relubrication Intervals for Greaselubricated Roller Bearings

Small bear ings with lateral seals or co ver plates do not

need any relubr ication . They are already for - l i fe lubric ated.

For al l other rol ler bear ing s relubr icat ion intervals become val id.


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Guidelines forRelubrication Intervalls

10 000

6 000

4 000

3 000

2 000

1 500

1 000

500

300

200

150

100

50

20 000

15 000

10 000

7 500

5 000

2 500

1 500

1 000

750

500

250

20 000

15 000

10 000

5 000

3 000

2 000

1 500

1 000

500

100 200 500 1 000 2 000 5 000 10 000n [U/min]

tfa

tfb

tfc

Lub ricat ion interval ,g iven by serv ice hours

tfa= radial ball bearing

tfb= cylindrical roller bearing / needle bearing

tfc= self alignin g roller bearing / taper roll ing bearing / axial roller bearing

massive cylin drical roller bearing (0,2 tfc), ax ia l cy li nd ri ca l ro ll er

bearing (0,5 tfc)

500 420 360 280 240 200 160 120 100 80 60

40

20

d=10

Example: A deep-groove ball bearing with an internal diameter

d= 100mm running at a speed of n = 1000 rpm. The operating

temperature lies between 60 and 70 C.

Which is the expected relubrication interval?

The vertical in point n= 1000 rpm on the abscissacuts the curve for d= 100mm. From there the horizontal leads

to the outer left-hand scale (deep- groove ball bearings)

indicating a relubrication interval of 10000 service hours


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Correction of Relubrication Intervals

The assessed intervals are valid only for:

lbear ings in s tat ionary machines

lno rmal load

lageing-proofed g reases

ltemperature < + 70C at the ou ter ring


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Dependance of RelubricationIntervals on Tempearture

100

85

70

55

40

Lubrication intervalC

Temperature at the outer ring

labov e 70C th e fac to r 0,5 appl ies

fo r eac h t emperatu re r is e of 15C

i.e. with a temperature ris e from e.g.

70C u p to 85C the serv ic e l if e o fthe grease is cut by half .

lb elow 70C the fac to r 2 app lies

fo r eac h t emperatu re d ro p o f 15C

i.e. wit h a temperature drop from e.g.70C down to 55 C the serv ic e li fe of th e

grease is dou bled.


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Lubrication by Oil

is used at high speeds resp. at DN-factors exceeding1.000.000 and in case heat conduction is necessary.


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Oil bath lubrication

Suitable only for bearings with low speeds.

During stand-stills the oil level should notquite reach the middle of the rolling element

at the bottom. .


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Oil injection lubrication

At high speed it becomes necessary,

that the air turbulence circulating with

the bearing is penetrated by the oil.

This is ensured by injecting oil under

high pressure (min.15 m/s) from the side

into the bearing.


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Circulatory oil lubrication

With increasing speed the service temperaturerises and accelerates the ageing of the

lubricating oil.

By circulatory lubrication the

oil can be cooled and consequently

the service temperature be reduced.

Cooling

pump


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Lubrication with Solid Lubricants

Deep groove ball bearings with increased clearance

required at:

lhigh temperatu res > + 200 C

lhigh temperature var iat ions

llow speed


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Lubrication with Solid Lubricants -Exsample

Lubr icat ion by Sol id

Lub r icants only

at temperatures > + 200 COKS 230 MoS2-High Temperatur e Paste(for thin-f ilm lub ricat ion durin g assembly and maintenance)

in connection with

OKS 310 MoS2-High -Temperatur e Lubric ant(for relubricat ion d uring o peration)

The carrying fluid evaporates residue-free above 200C and

dry MoS2 films remain, which assure lubrication up to 450C.

Kiln-car bearings in the ceramics and brick industry


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OKS Speciality Lubricants forRoller Bearings at:

lHigh loads

lShock stress

l

VibrationslLow or high speed

lStop-and-go operation

lVery low or very high temperatures

lTemperature variations

lHumid conditions

lCorrosive influences

lLong-term lubricating needs

lUse in the food industry


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Thank You

for Your

Attention

Date post:	02-Jun-2018
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